The amount of pee a diaper can hold and how many times you can pee in the diaper depends on the absorbency of the diaper you're wearing.
If you're wearing cheaper thinner disposable diapers you can usually pee around 3 or 4 times before they begin to leak.
For thicker more absorbent diapers such as the bambino diapers or diapers from Abuniverse diapers then you can get around 6 to 10 pees in the diaper before it begins to leak.
The thicker diapers cost more but they can last all day or almost all day depending on how much you pee in the diaper throughout the day.
So while you pay more per diaper for the thicker higher quality more absorbent diapers than you do with the cheaper diapers.
You can change diapers less and actually save money by buying the higher quality more absorbent diapers.